We purchased tables in wonderland this trip. It has already paid for itself on this one trip, but one thing that really bothered us was the fact that the tip was included and that was not advertised.
As you're well aware, the mandatory 18% service charge absolutely is publicized*, and that it doesn't have to be advertised. Only ONE server pointed out that the tip was included to us.
While that was considerate, most servers likely expect that Guests so familiar with WDW that they'd even have a Tables in Wonderland card would already know about the mandatory service charge. Our server at Tony's even folded the payment slip in such a way to hide the included tip section!
Talented
I know a little origami; I'd like to practice on dollar bills, but I can't seem to hold onto them long enough 
If we hadn't unfolded it, we wouldn't have noticed the included tip charge. That is just wrong. We are people that check receipts to make sure they are correct, but I suspect most people would just put in a tip and sign (especially after having a few drinks).
That's a surprisingly sorry opinion of other persons' behavior and responsibility
You make it sound as if you're the only people to display good judgment (hint: labeling something stupid and then laughing about it belies that self-assessment).
We felt that most of the servers were milking us for an extra tip. We love the program, but make sure you read your receipt!